The applicants represent five experienced core laboratories which plan to provide centralized, blinded analysis of endpoints for the TIMI III study of patients with unstable angina and non-Q-wave MI. Details of the TIMI IIIA and IIIB protocols are contained in the accompanying Clinical, Application. The Quantitative Angiography Core Laboratory (TIMI IIIA) has already provided quantitative assessment of over 1,600 coronary angiogram in prior studies, including TIMI I and II. This laboratory will identify changes in coronary artery stenosis and flow following t-PA therapy. The ECG/ETT Core Laboratory (TIMI IIIA and IIIB) has extensive experience in the use of the Minnesota Code This laboratory will confirm that ECG entry criteria are met, verify that ischemic ECG changes occurred during attacks of pain, and provide standardized interpretation of ECGs recorded during the ETT. The Ambulatory ECG (AEOG) Monitoring Core Laboratory (TIMI IIIA and IIIB), has in operation an advanced computerized system for the analysis of ST-segment changes on ambulatory ECG monitoring. It will provide data on otherwise undetected ischemic episodes following therapy--changes that are associate with poor prognosis. The Qualitative Angiography Core Laboratories (TIMI IIIB) will ensure the quality of angiographic studies and of PTCA, and assess the angiographic response to therapy--functions it is currently performing for TIMI II. The Radionuclide (Thallium) Core Laboratory (TIMI IIISB), which has already served as a core laboratory for TIMI II, will ensure the quality of stress thallium studies in the clinical units and utilize specialized method of analysis which it has developed to quantitate the thallium defect. A substantial portion of its cost will be provide by industry. Thus, these five core laboratories will provide the specialized analyses required for assessment of the results of therapy in these acutely ill patients. A special strength of the application is the prior experience of each of the laboratories with the tasks they will perform in TIMI III.